Electromagnetic apparatus



Au 7, 1945, T G. 1.. TAWNEY 2381 320 ELECTROMAGNETIC APPARATUS I I FiledNov. 28, 1940 Mumm- INVENTOR Gereld Zipbey. .BY

ATTORNEY WITNESSES? resonators is a difiicult matter.

Patented Aug. 7, 1945 2,381,320 ELECTROMAGNETIC APPARATUS 7 Gerald L.Tawney, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation,East Pittsburgh, Pa., a corporation of Pennsylvania Application November28, 1940, Serial No. 367,625

8 Claims.

My invention relates to apparatus for producing electromagneticphenomena and has particular relation to systems for generating,modifying, or utilizing high-frequency electromagnetic waves.

Hollow body resonators perform an'important function in the productionof phenomena involving a ultra-high-frequency radiation having a wavelength of the order of decimeters. The dimensions of a resonatordetermine the wave length of the radiant energy with which it isresonant. If very high-frequency radiation is involved, a smallresonator is, in accordance with the teachings of the prior art of whichI am aware, used. The alignmentand mounting of small hollow bodies sothat they function as Moreover, the frequency range over which hollowbody resonators may be used is limited on the higher frequency side bythe physical limitations involved in the construction of a. smallhollowbody.

In the case of short wave electromagnetic radiation efficiency is alsoan important consideration. The efiiciency of a resonatoras a functionof its dimensions is dependent on a quantity, Q, which may be computedfrom the relationship equation I 26fH dv I j'H ds where 6, (commonlycalled the skin depth) is a quantity determined from the thickness towhich the field penetrates into the surface of theresonator, .H is themagnetic field vector, v is a volume coordinate and sis a surfacecoordinate. The efliciency of a hollow body resonator is thus roughlydependent on the ratio of the volume to the surface, and, therefore,decreases roughly as its linear dimension is decreased.

' It is, accordingly, an object of my invention to provide a resonatorfor the generation, modification or utilization of electromagnetic wavesof very high frequency.

Another object of my invention is to provide an efflcient resonator, the.resonant frequency of which is very high- A specific object of myinvention is to provide a generator or an amplifier for electromagneticradiation of very high-frequency- More concisely stated, it is anobjectof in body resonators are frequency determining; elements; 1 I

larity in the appended claims.

. invention to provide an eificient ultra-high-fre quency generatororamplifier inwhich hollow conducting barrier determining apotentialnode in a hollow body resonator having convenient dimensions. Thefrequency at which the resonator may be excited to oscillate thuscorresponds to a harmonic of the fundamental frequencyof the resonator.A resonator of convenient dimensions with properly positioned nodedetermining barriers may be excited to oscillate at a relatively highfrequency. The Q function for a resonator of this type is dependent onthe dimensions of the complete hollow body and, therefore, issubstantial in spite of the fact that the resonant frequency may behigh.

The novel features that I consider characteristic of my invention areset forth with particu- The invention, however, both as to itsorganization and its method of operation, together with additionalobjects and advantages thereof, will best be understood from thefollowing description of specific embodiments when read in connectionwith the accompanying drawing, in which:

Figure 1 is a diagrammatic view partly in section and partly inperspective showing an embodiment of my invention;

Fig. 2 is a diagrammatic view partly in perspective and partly insection showing a modification of my invention; and

Fig. 3 is a view in perspective showing a portion of a resonator inaccordance with a further modification of my invention. I

While my invention is shown in the drawing as applied to an ultra shortwave oscillator, it is also applicable to an amplifier or'in any otherdevice for modifying,'utilizing or generating high frequencyelectromagnetic radiation. The apparatus' shown in Fig. 1 comprises anevacuated cylindrical container 5 of insulating material within which aplurality of hollow cylindrical shells l and 9 of substantially the samedimensions is mounted. The shells 1 and 9 are mounted centrallywithinthe container 5 with their axes coextensive and coincident with the axisof thecon'taine'r. The space within each shell is subdivided by a metalpartition II which. extends along a central symmetric plane. The basesI3 and I 5 of the shells have centrally disposed circular openings onboth sides of the partitions n and reentrant tubes |1,|9, 2|, '23, 25,21, 29 and 3| extend into the opening Sp The internal ends of the tubesare spaced a relatively short distance and are covered by an openwork33. The shellsv are so mounted that; the reentrant tubesll, I9, 25 and21 and 2|, Z3, 29

line. They may, for example, trace acircle coaxial with the; cylinder orhave any other configuration. The shells need not necessarily besubdivided by single partitions. circumstances several partitions may beinserted.

Under certain;

I, 9 The subdividing elements need not extend along and 53'ir'ithe'first shell 1 that the electrons are symmetric lines orsymmetric planes of the shell. They should, however, coincide-withthesnatural nodes corresponding to the electromagneticharmonies of theresonator. While hollow shells are to be preferred, the space within theshells niayunder certain circumstances in part with a suitableinsulating material.

"A plurality of electron emitting filaments 39 and are mounted in oneend of the container 5. :In the'opposite end'of the containeraplurality'of collectingelectrodes l3 and 45 is mounted. The geometriccenters of one of the filaments 39 and one of'the electrodes 43 lie onthe axes of oneset of aligned'reentrant tubes |1, |9, and 21 and thecenters Of the other filament 4| and collecting electrode 45 lieontheaxes of the other set of tubes 2|,- 23, 29 and 3|. A potential isimpressed between the collecting electrodes 43 and 45 and the filaments39 and 4| from a source 49 and electron streams emitted from thefilaments fiow through the reentrant tubes with which they are aligned.Preferably, fine electron streams are desired and for thisreasonsuitable apertures and constricting grids are provided for each.of the-filaments 39 and 4|. Since the apertures and grids do notconcern th present invention and are well-known in the cathode raytube-art and the general electronic artythey are not shown and describedin detail. Any suitable electron stream focusing system available in thecathode ray tube art may be used. Each electron stream passes throughthe open:- work ends 33 of the respectivereentrarit tubes 2| to 3l-withwhich it is aligned and issubl'ect to the electromagnetic field'sin thegaps 5| and 53, and 55 and 51"within the subdivisions of the shells 1and 9, respectively, formed by thepartitions I I as it passes betweenthe ends of the tubes |1 and |9.and 2| and 23, and 25 and 21-and 29 and3|,respectively'.

1 The distance between the ends 33 of the 're-' entrant tubes 2| to 3lin each of'the'shells 1 and 9 is short compared 'to the wave length towhich the subdivisions of the shellsare resonant.

i In passing through the gaps 5| and 53 of the? first shell 1 theirpath, the electron streams are subjected to the electric field vector ofthe high-frequency electromagnetic field with which the correspondingSubdivisions of the shell are resonant. "The field is periodic and has afrequency determinedby the'dimensions of thesaudivisions' of theresonator 1. Thespace' distribution of the field at any'instant isillustrated by the array of arrows 59 in the shell." The field has nodalregions in the external'wall of the'shell and in the partition." Betweenthe nodal points the field varies as an oscillating function. Thepolarity of the field in one division of the shell is opposite to thatin the adjacent subdivision;

ecause the reentrant tubes l1-and"|9 and 2|- and 23 are centrallymounted with respect'to the be filled wholly or the fields in the shellwall and the partition, the field is a maximum in the gaps 5| and 53.

As the streams pass through the gaps 5| and 53, the fields in the gapsimpress a periodic component on the velocity of their electrons. Becausethe velocity of electrons leaving the gaps at different instants variesperiodically, the electrons in each of thesstreams alternatelyaccumulate in bunches and separate as: they advance'. The gaps 55 and 51between the reentrant tubes 25 and 21 and 29 and 3|, respectively, ofthe second shell are so spaced from the corresponding gaps 5| groupedbunches when they pass through the i form p The field having the samefrequency as the distance between the gaps 5| and 55 and 53 and ,51 isso related to the electron speed that when the electrons reach the gaps55 and 51, gaps have a polarity such that they oppose the forward motionof the electrons. The fields in the gaps 55 and'51 absorb energy fromthe'electron streams. The energy may be radiated by an antenna 6|extending from loops 63 and 65' properly-oriented to be threaded by themagnetic field within the subdivisions of the shell 9'- Theloop's'63'and65 in the two subdivisions or the shell face in oppositedirections because the *magnetic fields by which they. are threaded areof opposite polarity and it is desired that the =electromotiveforcesinduced in the. loops shall add and not counteract each: other..Sufilcientenergy for modifying the electron speed is suppliedto themodulating shell-1 from theradiating' shell 9 by interconnected couplingloops 51 interconnected by a. conductor. I

Inaccordance-withthe preferred practice of my invention .anxelectronstream should beassociatedwitheacn of the subdivisions of the shells 1and 9.11:1 lieu of.:a plurality of streams asingle stream may be used.For example, the lower filament 4b in thefoslcillator shown inmaintained .deenergized and only the upper filament used tortransfer theenergy frornthe source 49totheiantenna6l. v

jFilaments 59: and 1|, and collecting electrodes 13 'and 'fl5'may; alsobe disposed, atppposite ends of the container 5, as shown in Fig. 2. Inthis case each of the shells .1 and 9 functions both as a modulator forthe: electron velocity and as an energy deriving device, one shell beinga modulator' forv one stream and .1 an energy deriving resonator'for''the other while the-other shell is an energy. deriving resonator for;the first stream and a'modulatorfor the second stream. Sincetherelisian interchange of ener ybetweenthe two shellsxthrough-theelectron streams in the Fig. ,2 arrangement; no coupling loop need beutilized. In oscillators of the type'zshown in Fig; 2,, the subdividingbarrier should preferably be ofithe type shown in Fig. 3 with thebarsspaced closely. The close spacing ;-is desirable. becausev thevelocity modulating energy should be relatively small and the energy ofthe absorbing: region relatively large. The bars when closely spacedpermit willcient' leakage between: the. subdivisionsv of "each of theshells for modulating purposes.

'Although I have shown and described certain specific embodiments of myinvention; 1 am fully aware that-many modifications thereof arepossiblef' My invention, therefore, is-not to berestricted exceptinsofar as is necessitated bytthe.

spirit of the appended-claims.

"I claim as my invention:

magnetic resonatorincluding "a first conducting Fig.1 may be shellhaving conducting means positioned therein subdividing the space boundedby said first shell, a plurality of electrodes mounted outside of saidfirst shell for projecting a stream of electrical charges through onesubdivision of said space bounded by said first shell, and a secondelectromagnetic resonator comprising a second conducting shell havingsecond conducting means therein subdividing the space bounded by saidsecond shell, one of the subdivisions of said second shell having thesame resonant frequency as said one subdivision of said first shell,said second shell being mounted with said one subdivision thereof in thepath of said stream between said first shell and one of said electrodeswhereby said stream passes through said one subdivision of said secondshell after it has passed through the subdivision of said first shell.

2. An electron tube comprising an electromagnetic resonator includin aconducting shell having conducting means therein subdividing the spacebounded by said shell, a plurality of electrodes mounted outside of saidshell for projecting a stream of electrical charges through onesubdivision only of saidspace, said conducting means being positionedparallel to the path of said stream and means positioned along the pathof said stream beyond said subdivision for producing an electromagneticfield in the path of said stream whereby said charges enter said fieldafter passing through said subdivision.

3. An electron tube comprising a first electromagnetic resonatorincluding a first conducting shell having a plane of symmetry andconduct: in means within said first shell and lying substantially insaid plane subdividing the space bounded by said first shell, aplurality of electrodes mounted outside of said first shell forprojecting a stream of electrical chargesthrough one subdivision of saidspace bounded by said first shell, said conducting means being parallelto the path of said stream and a second electromagnetic resonatorcomprising a second conducting shell having second conducting meanstherein subdividing the space bounded by said second shell, one of thesubdivisions of said secondshell having the same resonant frequency assaid one subdivision of said first shell, said second shell beingmounted with said one subdivision thereof in the path of said streambetween said first shell and one of said electrodes whereby said streampasses through said one subdivision of said second shell after it haspassed through the subdivision of said first shell.

4. An electron tube comprising a first electromagnetic resonatorincluding a first conducting shell having conducting means positionedtherein subdividing the space bounded by said first shell, a pluralityof electrodes mounted outside of said first shell for projecting astream of electrical charges through one subdivision of said space, saidconducting means being positioned parallel to the path of said stream, asecond electromagnetic resonator comprising a second conducting shellhaving second conducting means therein subdividing the space bounded bysaid second shell, one of the subdivisions of said second shell havingthe same resonant frequency as said one subdivision of said first shell,said second shell being mounted with said one subdivision thereof in thepath of said stream between said first shell and one of said electrodeswhereby said stream passes through said one subdivision of said secondshell after it has passed through said one subdivision of the firstshell, and means connected to said shells electromagnetically couplingsaid one subdivision of the first shell and said one subdivision of thesecond shell whereby said first resonator introduces a periodic. changein the motion of said charges, said second shell being spaced from saidfirst shell to receive the charges selectively and absorb energy fromthem.

5. An electron tube comprising an electromagnetic resonator including aconductin shell having conducting means therein subdividing the spacebounded by said shell, first electrode means mounted outside of saidshell for projecting a first stream of electrical charges through one ofsaid subdivisions, said conducting means being positioned parallel tothe path of said stream, second electrode means mounted outside of saidshell for projecting a second stream of electrical charges through asecond of said subdivisions, means positioned along the path of saidfirst stream beyond said first subdivision for producing anelectromagnetic field in the path of said first stream having afrequency resonant with said first subdivision, and means positionedalong the path of said second stream beyond said second subdivision forproducing an electromagnetic field in the path of said second streamhaving a frequency resonant with said second subdivision.

6.' An electron tube comprising an electromagnetic resonator including aconducting shell having conducting means therein subdividing the spacebounded by said shell, electrode means mounted outside said shell forprojecting a'stream of electrical charges through one subdivision onlyof the space bounded by said shell, said conducting means beingpositioned parallel to the path of said stream, and energy extractingmeans beyond said resonator and in the path of said stream coupled withthe interior of said subdivision for producing an electromagnetic fieldtherein having a frequency at which said subdivision is resonant tomodulate the velocity of said stream of charges.

'7. An electron tube comprising an electromagnetic resonator including aconducting shell having a plane of symmetry and conducting means lyingsubstantially in said plane within said shell subdividing the spacebounded thereby, electrode means mounted outside said shell forprojecting a stream of electrical charges through on subdivision only ofsaid space, said conducting means being positioned parallel to the pathof said stream, and energy extracting means positioned in the path ofsaid stream beyond said resonator for elfecting the production of anelectromagnetic field therein having a frequency at which saidsubdivision is resonant to modulate the velocity of said stream ofcharges.

8. An electron tube comprising an electromagnetic resonator including aconducting shell having a mode of oscillation and having aperturestherein defining an electron path conducting bars positioned within saidshell substantially parallel to the direction of said path andsubdividing the space bounded by said shell, electrode means mountedoutside said shell for projecting a stream of electrical charges alongsaid path through One subdivision only of said space, and meanspositioned in the path of said stream beyond said resonator forefiecting the production of an electromagnetic field therein having afrequency at which said subdivision is resonant to modulate the velocityof said stream of charges.

GERELD L. TAWNEY.

